1. Field of the Invention
The present invention relates to a display device which utilizes the subfield method to represent the brightness of halftones.
2. Description of the Related Art
Currently, display devices equipped with plasma display panels (hereafter called “PDPs”) or electroluminescence display panels (hereafter “ELDPs”) as thin-type planar display panels are known. In these PDPs and ELDPs, the emission elements in each pixel have only two states, “emitting” and “non-emitting”. Hence in order to obtain brightnesses of halftones corresponding to an input image signal, the subfield method is used in grayscale driving (multi-gradation level driving) of the display panels.
In the subfield method, an input image signal is converted into N bits of pixel data for each pixel, and the display period for one field is divided into N subfields corresponding to the N bits. To each subfield is allocated a number of emissions corresponding to the associated bit of the pixel data. When for example the logic level of one bit among the N bits is “1”, emission is executed in the subfield associated with that bit, the number of times allocated to that subfield. On the other hand, when the logic level of the bit is “0”, emission is not performed in the subfield associated with that bit. By means of this driving method, the brightness of halftones corresponding to the input image signal is represented by the sum of the number of times emission is executed in all the subfields within one field display period.